Economic historians and analysts face a conundrum comprehending South Asia. Just some decades ago the region was a single large market — with goods, services, capital investment and skilled labour flowing freely, and the newly independent countries inheriting a common historical, legal, cultural and administrative background and well-linked infrastructure. But today South Asia is the least integrated region in the world. Meanwhile, East Asia, whose countries possess diverse backgrounds and relatively little in common historically, has become the world’s most integrated region after the EU. There are many explanations, but the political tension and rivalry between South Asia’s two major players, India and Pakistan, is one key reason.